In recent years, the cloud computing using a network and a virtual machine (VM) is becoming popular. A plurality of servers may be placed in a data center used for the cloud computing, and the virtual machine operates in the server. The virtual machine transmits/receives data used for executing an application and execution results of the application to/from other virtual machines and servers. For this reason, communication may be carried out between a plurality of virtual machines in a data center. Furthermore, there may be a case in which a virtual machine operating on a server placed in a data center A communicates with a virtual machine operating on a server placed in a data center B that is different from the data center A.
As a related technique, a system in which virtual machines that provides service are gathered in a server included in a prescribed rack in a server room has been invented. This system seeks to save power with the change of the arrangement of the virtual machines by stopping the rack with no operating server and by stopping the processing of the equipment in the room for the rack.